Improved hoisting-block



- UNITED STATES PATENT OFFICE.

IMPROVED HOISTING-BLOCK.

Specication forming part of Letters Patent No. 33,929, dated December17, 1861.

Charlottetown, Prince Edward Island, have invented an ImprovedHoisting-Block, of which the following is a full, clear, and exactdescription, reference being had to the accompanying drawings, makingpart of this specification, in which- Figure l is a plan of the block,one side of the shell being removed. Fig. 2 is a section through theblock on the line o@ :l: of Fig. l; Fig. 3, a detail to be referred to.

The object of my present invention is to produce a hoisting-block (forships tackle and purchase blocks) which will combine the followingfeatures essential to a perfect block in a greater degree than any blockheretofore constructed with which I am acquainted: first, smallvsize andlightness in proportion to the amount of weight or strain the block iscapable of sustaining; second, the least amount of friction commensuratewith its strength; third, great strength and non-liability of thebearings to be crushed or deranged either vby a great strain appliedsuddenly to them or by a great weight suspended -for a long time on theblock; and my invention consists in a block having' a ring or centralbearing of considerable diameter cast onto or otherwise suitablyattached to the shell of the block and sur-rounded by a loose metalring, (which serves the purpose of the sheave of ordinary blocks) andbetween which and the central bearing` is interposed l stand and use myinvention, I will proceed to describe the manner in which I have carriedit out.

In the said drawings the shell of the block (which I prefer to have madeof brass or malleable iron) is divided into two halves A A2, which areheld together by bolts a, and nuts l). The block is furnished at one endwith a hook c and at the other with an eye or becket d. These are formedon the half A2 of the shell shown in Fig. 1, the cap-plate A being ofless thickness at its ends, where the bolts a pass through it. Bothparts have a circular opening B through the center.

From the inner face of the piece A2 rises a stout ring e, the outer edge3 of which is embraced by the cap A. There are formed in the face ofeach plate A A2 grooves f g exterior to the ring e, forming rings et 5 67, which project up from the face of each plate. Aheavy ring C is placedbetween the two plates A A2. It is turned out at h to receive the rope,like an ordinary sheave, and has a rib l on its inner side, which fitsbetween the rings 4 and 5. This ring C is of a somewhat greater diameterthan the rings 4 and 5 and revolves freely outside of them. Between thering C and the stationary ring e are placed friction-rolls m, of agreater diameter than the width of the grooves f and g, so that theyrest on the rings 4 5 and 6 7 and lill the space between the rings C ande, the loose ring C rolling around on these friction-rolls. To preventthese rolls m from running in contact with each other and grindingtogether, another series of rolls 0, of less diameter but of greaterlength,is introduced, one between each roll m. rolls o lie in thegrooves f and g and revolve freely therein.

Instead of the small rolls o, I sometimes employ blocks p, Fig. 3, whichare curved out on each side to match the rolls fm, and areintroducedbetween the rolls m to keep them separate, but are not intended toreceive the bearing of the ring C unless a weight should be applied tothe ring sufficient to crush the rolls fm or to indent them into thering. Before this, however, can take place to any considerable degreethe ring C will be supported by the blocks p (when these are used, as inFig. 3) or by the rings 4L and 5. Any required degree of strength may begiven to the ring e, while the form of the shell with the opening B inthe center allows the block to be made light in proportion to its powerand strength,

vor in some case where lightness is not so much an obj ect the shell maybe made wholethat is, without the opening B-and instead of the ring easolid disk may occupy the center of the block and serve as a bearing forthe friction-rolls m.

What I claim as my invention, and desire to secure by Letters Patent,is-

A hoisting-block having a loose metal ring C, (which takes the place ofthe sheave,) in combination with the central bearing e and thefriction-rolls m, operating substantially as specified.

VATSON DUCHEMIN.

Witnesses:

THos. R. RoAcH, P. E. TEscHMAcHER.

These i

